JP3251367B2 - Method for producing aromatic polycarbonate resin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aromatic polycarbonate resin particles. More specifically, the present invention relates to a method for easily producing aromatic polycarbonate resin particles having an extremely small amount of residual solvent and excellent quality from aromatic polycarbonate resin particles containing an organic solvent.

[0002]

2. Description of the Related Art An aromatic polycarbonate resin is usually produced by a so-called solution method in which an aqueous alkali solution of a dihydric phenol is reacted with phosgene in the presence of a solvent such as methylene chloride. After the powder is subjected to a granulation step of removing the powder into granules, it is subjected to a drying step. As a method of obtaining a powder by removing the solvent from the solvent solution of the aromatic polycarbonate resin,
For example, a method in which a solvent solution of an aromatic polycarbonate resin is brought into contact with hot water or steam to form flakes or granules (JP-B-36-11231, JP-B-40-9843, JP-B-45-9875, 48-43
No. 752, Japanese Patent Publication No. 54-122393), a method of gelation and granulation by concentration and cooling (Japanese Patent Publication No. Sho 3
No. 6-21033, Japanese Patent Publication No. 38-22497, Japanese Patent Publication No. 40-12379, Japanese Patent Publication No. 45-98
No. 75, JP-B-47-41421, JP-A-5
No. 1-41048) and the like are known. However, powders and granules (including flakes) obtained by these methods still contain a large amount of solvent, and it is difficult to sufficiently remove the residual solvent by ordinary drying.

As a method for removing the residual solvent, there has been proposed a method in which the residual solvent is mixed with hot water having a boiling point higher than the residual solvent and distilled. In this method, when the solvent is methylene chloride, it is not necessary to evaporate water, so that the temperature is gradually raised from about 40 to 50 ° C., and the residual solvent is removed by distillation at 90 to 100 ° C. in the final stage. . This method is extremely excellent in thermal efficiency, and can easily reduce the amount of residual solvent. However, several hundred to several thousand ppm of the solvent still remain in the powder obtained by this method. To further reduce the residual solvent, drying at a high temperature for a long time or pelletizing by an extruder equipped with a reduced pressure vent is used. Nevertheless, tens to hundreds of ppm of the solvent still remain, and the resulting product cannot avoid adverse effects on heat resistance, hue, physical properties and the like.

As a method for producing an aromatic polycarbonate resin powder having a small amount of residual solvent, a solvent solution of the aromatic polycarbonate resin obtained by the reaction or a slurry of the aromatic polycarbonate resin powder in which the solvent remains is mixed with a non-solvent or poor solvent. A method in which a solvent is added or a method in which an aromatic polycarbonate resin powder in which a solvent remains is extracted with a poor solvent (Japanese Patent Publication No. 55-1298, Japanese Patent Application Laid-Open No.
278929, JP-A-64-6020) and the like. In these methods, a good solvent is sufficiently removed, but a large amount of a non-solvent or a poor solvent remains. This residual non-solvent or a poor solvent is sufficiently removed not only by ordinary drying but also by drying at a high temperature for a long time. It is difficult.
In addition, when the drying is strengthened in this way, the molecular weight of the product is reduced, the hue is deteriorated, and foreign matter is mixed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to easily produce aromatic polycarbonate resin particles having an extremely small amount of residual solvent and excellent quality from aromatic polycarbonate resin particles containing an organic solvent. It is to provide a method that can do it. The present inventor has conducted intensive studies to achieve the above object, and as a result, when the aromatic polycarbonate resin particles containing an organic solvent were rapidly heated to a specific temperature and dried after heat treatment, the organic solvent was efficiently removed. It has been found that the aromatic polycarbonate resin powder obtained can be removed, and the above object can be achieved with almost no decrease in bulk density, decrease in molecular weight, deterioration of hue, contamination of foreign matter, and the like, thereby completing the present invention.

[0006]

According to the present invention, an organic solvent is used.
Water slurry of aromatic polycarbonate resin powder containing 0 to 65% by weight or powder obtained by dewatering the water slurry
At a temperature 30 ° C. or more higher than the boiling point of the organic solvent corresponding to the pressure, and at a temperature lower than the glass transition temperature of the aromatic polycarbonate resin constituting the powder and granules, followed by drying after heating in a heating solution. A method for producing an aromatic polycarbonate resin powder. In addition, organic solvents
Aromatic polycarbonate containing 10 to 65% by weight of medium
The water slurry of the resin particles is dewatered, and then, depending on the pressure,
Constituting the powdery granules higher than the boiling point of the organic solvent by 30 ° C. or more.
Below the glass transition temperature of the aromatic polycarbonate resin
At the temperature of, heat treatment in a heating vessel and then dry
Characterized in that the aromatic polycarbonate resin powder
It is a manufacturing method.

The good solvent, the non-solvent and the poor solvent referred to in the present invention are "Good Solvents" and "Fair Solvents" in the classification of "Polycarbonate" by WFCHRISTOPHER, DWFOX, Table 3-1 on pages 32-33, 1962, 1962. Solvents are good solvents, “PoorSolvents”, “Very
Solvents corresponding to "Poor Solvents" and "Weak Precipitants" are poor solvents, and solvents corresponding to "Nonsolvents" are nonsolvents. Representative examples of good solvents include methylene chloride, tetrachloroethane, and monochlorobenzene. Typical examples of the poor solvent include benzene, toluene, acetone, etc., and typical examples of the non-solvent include hexane, heptane, etc. The organic solvent referred to in the present invention is such a good solvent, It includes all non-solvents and poor solvents, and may be used alone or in combination of two or more.

[0008] The aromatic polycarbonate resin referred to in the present invention is an aromatic polycarbonate resin obtained by reacting a dihydric phenol with a carbonate precursor. The dihydric phenol used here has the following general formula

[0009]

Embedded image

[0010] [wherein W is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, alkylidene group, cycloalkylidene group, -S -, - SO -, - SO 2 -, - O- or -C
O—, X ₁ and X ₂ are an alkyl group having 1 to 3 carbon atoms or a halogen atom, and m and n are 0, 1 or 2. And at least one dihydric phenol selected from 4,4'-dihydroxydiphenyl represented by the formula: 2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A) It is preferably used. Other dihydric phenols include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4
-Hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, 4,4'-dihydroxydiphenyl, etc. And 2,2-bis (3,5
Halogenated bisphenols such as -dibromo-4-hydroxyphenyl) propane; Examples of the carbonate precursor include carbonyl halide, diaryl carbonate, and haloformate, and specific examples include phosgene, diphenyl carbonate, and dihaloformate of a dihydric phenol.

In producing the aromatic polycarbonate resin by reacting the dihydric phenol with the carbonate precursor, a catalyst, a molecular weight regulator, an antioxidant for the dihydric phenol and the like may be used as necessary. For example, a branched polycarbonate resin obtained by copolymerizing a polyfunctional aromatic compound having three or more functional groups, or a polyester carbonate resin obtained by copolymerizing an aromatic and / or aliphatic difunctional carboxylic acid may be used. It may be a mixture of two or more aromatic polycarbonate resins. There is no particular limitation on the molecular weight of the aromatic polycarbonate resin, and it is usually 13,000 to 50, expressed in terms of viscosity average molecular weight.
000 is preferred.

The powder of the above-mentioned aromatic polycarbonate resin which is the object of the present invention may be produced by any method, and may have any shape, and the size of the powder is usually about the size of a powder or granule. It is not necessary to limit anything as long as the size is one, and the total content of one or more organic solvents is 10 to
65% by weight of aromatic polycarbonate resin particles. Note that the water content is not limited at all. If the content of the organic solvent is less than 10% by weight, it is difficult to obtain the effect of the present invention. In this case, if it is necessary to carry out the method of the present invention, the organic solvent may be added in a predetermined amount. If the content of the organic solvent is more than 65% by weight, it becomes difficult to handle the powder as a granule, which is not suitable. In this case, the amount of the organic solvent may be reduced to a predetermined amount by appropriate means such as heating.

In the method of the present invention, the aromatic polycarbonate resin powder containing the above-mentioned predetermined amount of the organic solvent is heated at a temperature higher than the boiling point of the contained organic solvent by 30 ° C. or more. The temperature is rapidly increased at a temperature lower than the glass transition temperature of the constituent aromatic polycarbonate resin, and heat treatment is performed. This heat treatment significantly improves the subsequent drying efficiency and allows normal drying conditions to dry to residual solvent amounts that could not be achieved by the conventionally enhanced drying conditions. This temperature is 30 ° below the boiling point of the organic solvent.
When the temperature is lower than the high temperature, it is difficult to obtain the effect of improving the drying even if the heat treatment is performed for a long time. When the temperature is higher than the glass transition temperature of the aromatic polycarbonate resin, agglomeration occurs and pulverization is performed again. This necessitates the generation of fine powder and the increase of foreign substances, and furthermore, the decomposition of the organic solvent becomes intense, and the corrosion of used equipment rapidly increases. Here, the boiling point of the organic solvent is the boiling point of the organic solvent according to the pressure of the atmosphere for heat treatment. If the atmosphere for heat treatment is under pressure, the boiling point under the pressure is referred to. When a solvent is contained, the boiling point of the organic solvent having the lowest boiling point is targeted.

If the temperature is raised slowly, it is difficult to obtain the above-mentioned effect of removing the solvent even if the heat treatment is performed for a long time.
It should be as fast as possible, and it is preferred to heat so as to reach the predetermined temperature within about 5 minutes. Any method may be employed as a method for rapidly increasing the temperature to a predetermined temperature, but a method in which the aromatic polycarbonate resin particles are charged into an atmosphere maintained at the predetermined temperature is preferable. The atmosphere may be any of gas, liquid, and solid.For example, water, water vapor, non-solvent, air, powder and the like having the same quality as the powder to be heat-treated are arbitrarily used. The supply may be discontinuous or continuous, or the atmosphere may be heated by a jacket or a heater. The heat treatment time performed by rapidly raising the temperature to a predetermined temperature is preferably 10 minutes or more, since the treatment effect is reduced if the temperature is too short.
About 100 minutes is enough. As this heat-up heat treatment device, any device, for example, even a simple tank type,
Dryers such as paddle dryers, multi-fin dryers, drum dryers, band dryers, fluid dryers, hot air dryers, etc. may be used, but poor solvents and non-solvents are present as organic solvents contained in the powder. When doing so, it is preferable to use an explosion-proof type.

The drying performed after the heat treatment may be performed under the conditions usually employed for drying the aromatic polycarbonate resin particles, and the apparatus may be any dryer. This drying may be performed subsequent to the heat treatment, and is preferably performed for about 4 to 8 hours in consideration of generation of fine powder, mixing of foreign matter, and the like. Also in this case, when a poor solvent or a non-solvent exists as the organic solvent to be dried and removed, it is preferable to use an explosion-proof type. In addition, when the heat treatment is sufficiently performed for a long time, the drying step may be omitted.

[0016]

EXAMPLES Examples will be further described below with reference to examples. In addition,
% In the examples is% by weight, and the evaluation was made by the following method.

(A) Methylene chloride: The chlorine content was determined by analyzing with a total organic halogen analyzer [TOX manufactured by Mitsubishi Kasei Co., Ltd.].

(B) Determination of n-heptane, n-hexane and acetone: Gas chromatography [type 263 manufactured by Hitachi, Ltd.], using dioctyl sebacate as a column packing material, and headspace method at 250 ° C. It was measured.

(C) Foreign matter quantity (pieces / g): 20 g of the polymer was dissolved in 2,000 ml of methylene chloride, and the concentration of the foreign matter in each particle size distribution was scattered by a liquid particle counter (HIAC / ROYCO) using a laser sensor. 0.5 μm
The above foreign substances were measured.

(D) Viscosity average molecular weight (M):
A specific viscosity (η _sp ) is measured from a solution obtained by dissolving 7 g in 100 ml of methylene chloride at 20 ° C. using an Ostworld viscometer and calculated by the following equation. Η _sp / C = [η] + K [η] ² C [η] = 1.23 × 10 ⁻⁴ M ^0.83 (where C is 0.7 in concentration and K is 0.45 in constant)

(E) Hue (b value): 50 mm by injection molding
A sample plate of × 50 mm × 5 mm was molded and measured by a color difference meter [manufactured by Suga Test Instruments Co., Ltd.] in accordance with JIS K-7105 Z8722. A smaller value indicates a smaller yellow tint.

(F) Average particle size (mm) and particle size distribution (n): According to the particle size measurement method described in Chapter 1, Section 2, 2.4 of "Granulation Handbook" edited by Japan Powder Industry Association. It was measured. In the Rosin-Rammler equation, n is a measure of the particle size distribution, and a larger value indicates that the width of the particle size distribution is narrower.

[0023]

Example 1 (A) A 15% methylene chloride solution of an aromatic polycarbonate resin having a viscosity average molecular weight of 23,500 (glass transition temperature: 149.3 ° C.) obtained from bisphenol A and phosgene by a conventional method was charged into a kneader. After removing the methylene chloride, the mixture was coarsely pulverized and then pulverized by a hammer mill equipped with a screen having a mesh of 5 mm to obtain a water slurry having an aromatic polycarbonate resin particle concentration of 25% and a liquid temperature of 35 ° C. The methylene chloride content of the aromatic polycarbonate resin particles was 25%.

(B) This water slurry is poured into hot water kept at 95 ° C. under normal pressure with stirring, heat-treated under heating and stirring for 1 hour, and then dehydrated by a centrifugal separator to obtain a methylene chloride content of 0.9%. Thus, an aromatic polycarbonate resin powder having a water content of 12% was obtained. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0025]

Example 2 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was poured into hot water maintained at 75 ° C. under normal pressure with stirring, and heat-treated under heating and stirring for 1 hour. Dehydrate by centrifugal separator, methylene chloride content 2.5
% And a water content of 9% were obtained. Next, the powdery granules were removed by a paddle dryer to 14 g.
Dry at 5 ° C. for 5 hours. Table 1 shows the evaluation results of the dried granules.

[0026]

Example 3 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was dehydrated by a centrifuge to obtain an aromatic polycarbonate resin particles having a water content of 8%.
This powder was poured into hot n-heptane kept at 85 ° C. under normal pressure with stirring, heat-treated under heating and stirring for 1 hour, dehydrated by a centrifugal separator, and methylene chloride content 700 ppm, n
-An aromatic polycarbonate resin powder having a heptane content of 1.01% was obtained. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0027]

Example 4 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was dehydrated by a centrifugal separator to obtain aromatic polycarbonate resin particles having a water content of 8%. The granules were put into a fluidized dryer through which hot air of 120 ° C. was passed and heat-treated for 1 hour to obtain aromatic polycarbonate resin granules having a methylene chloride content of 4,900 ppm and a water content of 1,500 ppm. Was. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0028]

Example 5 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was dewatered by a centrifugal separator to obtain aromatic polycarbonate resin particles having a water content of 8%. The granules are put into a 145 ° C. drum dryer containing the aromatic polycarbonate resin granules and heat-treated for 1 hour, and the methylene chloride content is 1600 ppm and the water content is 2,000 ppm. I got a body. Next, the drum dryer was used for 145
Dry at 5 ° C for 5 hours. Table 1 shows the results of the evaluation of the dried granules.
It was shown to.

[0029]

Example 6 Aqueous slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A)
% Hexane was added with stirring and mixed for 20 minutes, then poured into hot water kept at 80 ° C. under normal pressure with stirring, heat-treated under heating and stirring for 1 hour, dehydrated by a centrifuge, and methylene chloride content 400 ppm. , Hexane content 7,800ppm
Thus, an aromatic polycarbonate resin powder having a water content of 2.5% was obtained. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0030]

Example 7 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A)
% Of n-heptane was added under stirring and mixed for 20 minutes, and then dehydrated by a centrifuge to obtain a methylene chloride content of 10%.
-An aromatic polycarbonate resin powder having a heptane content of 18% and a water content of 1.8% was obtained. The granules were put into a paddle dryer at 145 ° C. containing the aromatic polycarbonate resin granules and heat-treated for 1 hour, and the methylene chloride content was 200 ppm, the n-heptane content was 8,900 ppm,
An aromatic polycarbonate resin powder having a water content of 1,800 ppm was obtained. Then use the paddle dryer as it is 1
Dry at 45 ° C. for 5 hours. Table 1 shows the evaluation results of the dried granules.

[0031]

Example 8 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was dewatered by a centrifugal separator to obtain aromatic polycarbonate resin particles having a water content of 8%. This powder was poured into hot water maintained at 120 ° C. by stirring with a screw feeder, heat-treated under heating and stirring for 1 hour, and then dehydrated by a centrifugal separator to obtain a methylene chloride content of 5,000 ppm and a water content of 8%. An aromatic polycarbonate resin powder was obtained. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0032]

Comparative Example 1 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A) was poured into warm water maintained at 45 ° C. under normal pressure with stirring, and maintained at 95 ° C. for 1 hour.
After the temperature was raised to and maintained for 1 hour, dehydration was performed by a centrifugal separator to obtain an aromatic polycarbonate resin powder having a methylene chloride content of 2.1% and a water content of 12%. Next, the powder was dried at 145 ° C. for 5 hours using a paddle dryer. Table 1 shows the evaluation results of the dried granules.

[0033]

Comparative Example 2 The procedure of Comparative Example 1 was repeated except that the drying time with a paddle dryer was changed to 10 hours. Table 1 shows the evaluation results of the dried granules.

[0034]

Comparative Example 3 A water slurry of the aromatic polycarbonate resin particles obtained in Example 1 (A)
% N-heptane was added with stirring and mixed for 20 minutes.
The mixture was poured into warm water maintained at 50 ° C. under normal pressure with stirring, maintained for 1 hour, gradually heated to 95 ° C., further maintained for 1 hour, and then dehydrated by a centrifuge to remove methylene chloride.
An aromatic polycarbonate resin powder having 0 ppm, an n-heptane content of 3.8% and a water content of 7% was obtained. Next, the powder was dried with a drum dryer at 145 ° C. for 5 hours. Table 1 shows the evaluation results of the dried granules.

[0035]

[Table 1]

[0036]

According to the method of the present invention, aromatic polycarbonate resin particles having a very small amount of residual solvent can be obtained by a simple heat treatment, and the resulting aromatic polycarbonate resin particles have a reduced bulk density and a reduced molecular weight. There is almost no decrease in color and deterioration of hue, there is little contamination of foreign matter, and further, the particle size characteristics are excellent, and the industrial effects achieved are outstanding.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tatsumi Horie 1-6-21 Nishishinbashi, Minato-ku, Tokyo Teijin Chemicals Co., Ltd. (56) References JP-A-5-17579 (JP, A) 54-101771 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 64/00-64/42 C08J 3/12

Claims (2)

(57) [Claims] A water slurry of an aromatic polycarbonate resin powder containing 10 to 65% by weight of an organic solvent or
The powder obtained by dehydrating the water slurry, at a temperature lower than the glass transition temperature of the aromatic polycarbonate resin constituting the powder by 30 ° C. or more higher than the boiling point of the organic solvent depending on the pressure,
A method for producing an aromatic polycarbonate resin powder, which is characterized by rapidly heating and then drying in a heated solution . 2. A solvent containing 10 to 65% by weight of an organic solvent.
Dewaters water slurry of aromatic polycarbonate resin particles
And then 30 ° C from the boiling point of the organic solvent according to the pressure.
Aromatic polycarbonate tree which constitutes the powdery material above high
At temperatures below the glass transition temperature of the fat
Aromatic polycarbonate characterized by drying after heat treatment
A method for producing a carbonate resin granule.